Death Finds a Way: A Janie Riley Mystery by Lorine McGinnis Schulze. Janie Riley is an avid genealogist with a habit of stumbling on to dead bodies. She and her husband head to Salt Lake City Utah to research Janie's elusive 4th great-grandmother. But her search into the past leads her to a dark secret.
A: The most abundant isotope of magnesium has 12 neutrons; it is therefore, technically known as magnesium-24. Calculating the number of neutrons in an isotope of any element involves subtracting that element's atomic number from its atomic weight. Magnesium's number is 12, and its weight is just over 24.
Atomic number and mass number. The atomic number of an atom is the number of protons it contains. All the atoms of a particular element have the same atomic number (number of protons). The atoms of different elements have different numbers of protons. For example, all oxygen atoms have 8 protons and all sodium atoms have 11 protons. The mass number of an atom is the total number of protons and neutrons it contains. The mass number of an atom is never smaller than the atomic number. It can be the same, but is usually bigger.